Method for extruding multicolored sheet material



J. P. NAUTA Nov. 17, 1970 METHOD FOR EXTRU'DING MULTICOLORED SHEETMATERIAL 5 Sheets-Sheet 1 Original Filed 001;. 22, 1965 FIG:

INVENTOR. JAN P NAUTA ATTORNEY n I R E T A M T E E H S D m A0 m UC M mRM .6 m R T X E R O F D O H T E M Nov. 17, 1970 3 Sheets-Sheet 2Original Filed Oct.

I INVENTOR. JAN P. NAUTA ATTORNEY J. P. NAUTA Nov. 17, 1970 METHOD FOREXTRUDING MULTICOLORED SHEET MATERIAL 3 Sheets-Sheet 3 Original FiledOct. 22, 1965 FIG m mm m WM I P N A J @464 ATTORNEY United States PatentO 3,540,964 METHOD FOR EXTRUDING MULTICOLORED SHEET MATERIAL Jan P.Nauta, West Hartford, Conn., assignor to Rowland Products, Incorporated,Kensington, Conn., a corporation of Connecticut Original applicationOct. 22, 1965, Ser. No. 500,775, now Patent No. 3,443,278, dated May 13,1969. Divided and this application Oct. 18, 1968, Ser. No. 768,740

Int. Cl. B29c 9/00 U.S. Cl. 156-244 6 Claims ABSTRACT OF THE DISCLOSUREA method is provided for extruding thermoplastic sheet material havingdifferentially colored layers wherein differentially colored streams ofthe thermoplastic material are caused to flow in vertical layers and arecombined in the extruder into a composite stream. The thermoplasticsheet material having differentially colored layers and in variouspatterns is also disclosed.

REFERENCE TO RELATED APPLICATION The present application is a divisionof my copending U.S. application Ser. No. 500,775, filed Oct. 22, 1965,now U.S. Pat. No. 3,443,278, granted May 13, 1969.

BACKGROUND OF THE INVENTION Oftentimes, the provision of extruded sheetmaterial with differentially colored layers, or layers and bands, isdesirable, particularly for novel decorative effects. Generally, suchbands or layers of color extend parallel to the direction of extrusion,and a highly effective apparatus and method for making one form ofdifferentially colored material are described in U.S. Pat. No.2,985,556, granted May 23, 1961, to William P. Rowland, reissued as U.S.Pat. No. Re. 26,237, dated July 18, 1967.

The term differentially colored material is intended to encompassmaterials which are visually distinguishable from each other or a firstcolor to provide a visual pattern effect and includes materialscontaining coloring matter such as dyes and pigments and materials whichare substantially transparent to provide distinct coloration and the useof streams of the same color which have distinct optical properties suchas by incorporation of optically modifying components such as aluminumflakes which produce variation in light refraction or transmission withresultant visual pattern effect.

It is an object of the present invention to provide a novel andattractive synthetic plastic sheet material having generallylongitudinally extending layers of differentially colored material whichmay provide a wide variation in patterns.

It is also an object to provide a relatively simple and highlyeflicacious method of extruding synthetic plastic sheet material havinglongitudinally extending layers of differentially colored material whichis adapted to wide variation in pattern design.

Still another object is to provide a method for making multilayeredsheet material wherein the thickness of the layers may be varied acrossthe width of the sheet material.

A specific object is to provide a method for making such syntheticplastic sheet material having differentially colored layers which isparticularly adapted for convenient fabrication of eyeglass frames.

SUMMARY OF THE INVENTION It has now been found that the foregoing andrelated objects and advantages may be readily attained in a meth- 0dwherein there are provided a first stream of fluid thermoplasticmaterial and a second stream of a differentially colored fluidthermoplastic material. The two streams are passed through separatemanifolds in a color distributing stack having a multiplicity of spacingand flow elements so that the material from one stream is caused to flowthrough a flow element and the material from the other stream is causedto flow through another flow element spaced above the first mentionedflow element and separated therefrom by a spacing element. Thethermoplastic material issuing from the flow elements combines in theextruder outwardly of the color distributing stack to provide acomposite stream having differentially colored layers in at least aportion of the width thereof. The composite stream then is extruded toprovide thermoplastic sheet material having differentially coloredlayers in at least a portion of the width thereof.

The method of the present invention desirably utilizes an extrusionapparatus comprising an extrusion die member having a chamber thereinand an extrusion orifice in one surface thereof which communicates withthe chamber, a first conduit for supplying a first stream of fluidsynthetic thermoplastic material to the chamber at a first point spacedfrom the extrusion orifice and a second conduit for supplying a secondstream of differentially colored fluid synthetic thermoplastic materialto the chamber at a second point spaced from the first point and fromthe extrusion orifice with the conduits extending from surfaces otherthan that having the extrusion orifice.

A color distributing stack comprised of a multiplicity of spacer andflow elements is disposed within the chamber of the extrusion die memberand has a plurality of manifolds extending therethrough adjacent the endthereof spaced from the extrusion orifice. Various of the manifoldscommunicate with one of the conduits and others communicate with theother conduit so as to provide flow of material from both of saidconduits through the manifolds. The flow elements have at least oneaperture or flow path therein extending from one of the manifolds to theother end of the stack adjacent the extrusion ori fice to provide forflow therethrough, and at least two flow elements have overlyingapertures extending from manifolds communicating with different conduitsso as to provide superposed flow of thermoplastic material from both ofthe conduits in at least a portion of the stack. A spacer elementseparates the two flow elements from the manifolds for at least aportion of the distance to the end of the stack adjacent the extrusionorifice after which the superposed flowing materials from the twoconduits may combine to produce a synthetic plastic sheet materialhaving differentially colored layers in at least a portion of the Widththereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.-1 is a fragmentary end view ofone embodiment of synthetic plastic sheet material extruded inaccordance with the present invention;

FIG. 2 is a fragmentary plan view of an extruder as sembly embodying thepresent invention;

FIG. 3 is a side sectional view to an enlarged scale of the extruder dieassembly of FIG. 2;

FIG. 4 is a plan view of a spacing element in the color distributingstack of the extruder die assembly in FIG. 3;

FIG. 5 is a plan view of a flow element in the color distributing stackthereof;

FIG. 6 is a plan view of another flow element in the color distributingstack thereof;

FIGS. 7-9 are plan views of flow elements in another color distributingstack of the present invention;

FIG. is a fragmentary end view of synthetic plastic sheet materialextruded with a color distributing stack utilizing the flow elements ofFIGS. 7-9;

FIGS. 11 and 12 are plan views of flow elements in another colordistributing stack of the present invention;

FIG. 13 is a fragmentary end view of synthetic plastic sheet materialextruded with a color distributing stack employing the flow elements ofFIGS. 11 and 12;

FIG. 14 is a plan view of an alternative embodiment of spacer element;

FIG. 15 is a side elevational view thereof;

FIG. 16 is a front elevational view thereof;

FIG. 17 is a fragmentary end view of synthetic plastic sheet materialextruded with a color distributing stack employing spacer elements ofthe type illustrated in FIGS. 14-16;

FIG. 18 is a sectional view along the line 18-18 of FIG. 3;

FIG. 19 is a side elevational view in section of the color distributingstack of FIG. 3 to a greatly enlarged scale;

FIG. 20 is a fragmentary front elevational view of another embodiment ofcolor distributing stack of the present invention;

FIG. 21 is a fragmentary end view of synthetic plastic sheet materialextruded with the color distributing stack of FIG. 20;

FIG. 22 is a plan view of another embodiment of spacing element for acolor distributing stack; and

FIG. 23 is a fragmentary end view of synthetic plastic sheet materialextruded with a color distributing stack employing the spacing elementof FIG. 22.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring first indetail to FIG. 1 of the attached drawings, there is fragmentarilyillustrated in end view synthetic plastic sheet material extruded inaccordance with the present invention comprised of a plurality of layers2 of a first color and layers 4 alternating therewith of adifferentially colored material.

Referring next to FIGS. 2, 3, l8 and 19, therein illustrated isapparatus for extruding the sheet material of FIG. 1. Referring inparticular to FIG. 3, an extruder assembly embodying the presentinvention is generally comprised of an extrusion die block assemblygenerally designated by the numeral 6, a first extruder and conduitassembly generally designated by the numeral 8 and a second extruder andconduit assembly generally designated by the numeral 10. The mainstreamof plastic material to supply one of the layers 2, 4 is fed into theextrusion die assembly through the mainstream duct portion 12 of theextruder and conduit assembly 8. Before entering the duct portion 12,the plastic material passes through the heating section 14 of theconduit which is coupled to the intake section 16 by the collar assembly18. To supply and melt the plastic material a conventional extruder isprovided wherein a motor 20 drives the feed screw 22 to draw syntheticplastic pellets 24 stored in the hopper 26 through the heating section14 of the conduit wherein a series of heating elements 28 melts thepellets 24 into a fluid stream of synthetic thermoplastic material.

A stream of fluid synthetic thermoplastic material for the other of thelayers 2, 4 is supplied to the extrusion die assembly 6 by the secondextruder and conduit assembly 10 wherein the conduit similarly includesa heating section 30 wherein the heating elements 32 melt the pellets 34in the hopper 36 to provide a fluid stream of synthetic thermoplasticmaterial as the are moved along by the screw 38. The intake section 40is coupled to the heating section 30 through the collar assembly 42 andhas a tubular portion 44 extending across the die assembly 6 which islocked within the die assembly by the flanged cap 46.

Referring next to FIGS. 3 and 18, it can be seen that the die blockassembly 6 has an elongated chamber 48 therein with a generallyrectangular portion tapering to a reduced thickness adjacent anelongated extrusion orifice 50 defined by the die lips 52 in the frontface of the extrusion block assembly 6. The tubular portion 44 isdisposed above the chamber 48 and the mainstream duct portion 12 fansout to an increased width and extends below the chamber 48.

Seated and locked within the chamber 48 is a color distributing stackgenerally designated by the numeral 54 which is comprised of alternatelydisposed plate-like flow elements 56, 58 separated by plate-like spacerelements 60. Extending downwardly from the tubular portion 44 of theextruder and conduit assembly 10 are a plurality of conduit portions 62which communicate with manifolds or flow paths through the colordistributing stack 54 defined by aligned apertures 64 in the flowelements 56, 58 and spacer elements 60. Extending upwardly from themainstream duct portion 12 are a plurality of conduit portions 66 whichcommunicate with manifolds defined by the apertures 68 in the flowelements 56, 58 and spacer elements and best seen in FIGS. 4-6. As canbe seen, the manifolds defined by apertures 64, 68 alternate so as toprovide adjacent flow paths for material from the two conduit assemblies8, 10.

The apertures 64 in the flow elements 56 are notched outwardly so thatthe apertures expand and the adjacent sides thereof converge toward theextrusion die orifice '50 to provide expanding paths for the syntheticplastic material flowing therethrough from the manifolds communicatingwith the tubular portion 44 of the conduit assembly 10. The apertures 68in the flow elements 58 are similarly notched outwardly to provideexpanding paths for synthetic plastic material flowing therethrough fromthe manifolds communicating with the mainstream duct portion 12. It canbe seen that the expanding apertures in the flow elements 56, 58alternate across the width of the color distributing stack. The flowelements 56, 58 and spacer elements 60 are pinned together in a stackagainst relative displacement by elongated fasteners 70 seated in theapertures 72 of the members 56, 58 and 60.

Thus, in operation of this particular embodiment, molten material of afirst color from the extruder and conduit assembly 10 enters into theextrusion die assembly 6 through the tubular portion 44, and passesdownwardly through the conduit portions 62 into the manifolds 64 of thecolor distributing stack 54. As it flows through the flow elements 56,it is allowed to flow outwardly through the notched-out aperturesbetween the spacer elements 60. Similarly, differentially colored moltenthermoplastic material from the extruder and conduit assembly 8 flowsinto the mainstream duct portion 12 and upwardly through the conduitportions 66 into the manifolds 68 in the color distributing stack 54. Asit flows through the flow elements 58, it is permitted to flow outwardlyin the notched-out portions between the spacer elements 60. As thestreams of material flowing within the notched-out apertures of the flowelements 56, 58 pass outwardly of the spacer elements 60, they combineinto a multi-layered stream with alternating layers of differentiallycolored material. This stream is then directed by the configuration ofthe extrusion chamber 48 to the extrusion orifice 50 defined by the dielips 52 wherein its final configuration is established in terms of widthand thickness, to produce sheet material substantially as illustrated inFIG. 1.

Referring now to FIGS. 7-10, flow elements of the type illustrated inFIGS. 7-9 are used to produce the sheet material of FIG, 10 wherein twolayers containing differentially colored bands alternate with a thirddifferentially colored material and also taper in width through thedepth or thickness of the sheet material. The flow elements specificallyillustrated in FIGS. 7-9 represent those utilized in fabricating theupper portion of the sheet material of FIG. 10. As can be seen, each ofthe flow elements 74, 76 and 78 has a multiplicity of apertures 80, 82and 84 across the width thereof which provide manifolds connecting tothree conduits each carrying a differentially colored material. The flowelement 74 has the apertures 80 therein communicating with conduits ofthe same color so that the layer formed thereby is of a single color asrepresented by the numeral 86 in FIG. 10.

The flow element 80 of FIG. 8 has the apertures 82 at either sidethereof communicating with a conduit of a second color and the centralaperture 80 therein communicating with the conduit for the same color asthat utilized by the flow element 74. In this manner, two bands of asecond color represented by the numeral 88 in FIG. are provided in thelayer formed thereby with the first color disposed therebetween. Theflow element 78 has the apertures 84 at either side thereofcommunicating with a conduit for a third color and the central aperture80 communicating With the conduit for the first color utilized bytheflow element 74. Thus, this flow element provides two bands of a thirdcolor indicated by the numeral 90 in FIG, 10 to either side of a centralportion of the first color.

In assembling the remaining portion of the color distributing stack, theflow element 74 of FIG. 7 is again repeated and the flow elements 76, 78of FIGS. 8 and 9 have the shape of the notched-out apertures 82, 84,respectively, modified to an increasing extent to reduce the widththereof and the width of the apertures 80- expanded to compensate forthis reduction. Thus, the bands of the second and third colors arereduced in width through the depth of the sheet material as illustrated.

Referring now to FIGS. 11-13, the flow elements 92, 94 of FIGS. 11 and12 are used to fabricate the sheet material of FIG. 13. As can be seen,the flow element 92 has a series of notched-out apertures 96, 98, whichalternate across the flow element and provide manifolds communicatingwith two conduits for differentially colored material. The flow element94 has apertures 96, 98 therein which also alternate across the width ofthe flow element but which are not all notched out so that flow is notobtained from all conduits. Both flow elements are asymmetric in termsof the notched-out apertures 96, 98 and of the width of the aperturesadjacent the extrusion die orifice so that reversal of the flow elements92, 94 will produce a different orientation of colored material issuingfrom the manifolds therein.

In forming the sheet material of FIG. 13, the layer 100 is provided bythe fiow element 94 as illustrated and the layer 102 is provided by theflow element 92 as illustrated. The layer 104 is provided by the flowelement 94 in reversed position, the layer 106 is provided by the flowelement 94 as illustrated and the layer 108 is provided by the flowelement 92 in reversed position. Thus, layers have the color bands A, Bvarying in location across the width of the sheet material.

Referring now to FIGS. 14-17, the spacer element 110 has the edgeportion 112 thereof to be disposed adjacent the extrusion die orificecorrugated as best seen in FIGS. and 16 so as to provide undulationstherein. These undulations produce disturbance in the flow of materialfrom the flow elements thereabove and therebelow so as to produce anonrectilinear layered structure of the type illustrated in FIG. 17.

Referring now to FIGS. and 21, the flow elements 120, 122 thereof havethe notched-out apertures 124, 126 therein opening to a relatively largewidth with respect to the thickness of the stock from which the elementsare formed, and have spacer elements 128 therebetween. By controllingthe pressure of the thermoplastic material in the conduits, the flowfrom adjacent apertures 124, 126 in the adjacent flow elements 120, 122will produce lesser pressure in the expanded portions of the apertures124, 126, than in the area in alignment with the manifold diameter.Accordingly, the aligned manifold portion of an aperture in one flowelement will align with the widely divergent portion of an aperture inthe adjacent flow element and the pressure of the material thereat willdistort the uniformity of the thickness of that stream due to the lesserpressure in the stream thereabove or therebelow and produce undulationsin the width of the layers as illustrated in FIG. 21.

Referring now to FIGS. .22 and 23, the spacer element 130 has its edgeadjacent the extrusion die orifice provided with a recess 132 which isof maximum depth adjacent one side and tapers outwardly toward theextrusion die orifice. Such a spacer element when placed between flowelements apertured so as to provide the same color will create reducedresistance to flow of that color through those flow elements at therecessed portion and increase the amount and pressure of materialissuing thercat. This increased flow will depend upon the depth of therecess at that point and the increased pressure of this colored streamwill produce deflection in the streams of the differentially coloredmaterial disposed thereabove and therebelow to produce a sheet materialas indicated in FIG. 23. As can be seen, the layer 134 of the firstcolor provided by a pair of flow elements separated by the recessedspacer element 130 tapers to a reduced thickness toward the center ofthe sheet material and the layers 136 of the differentially coloredmaterial taper to a reduced thickness toward the side edge of the sheetmaterial.

As can be seen from the foregoing specific illustrations andembodiments, a high degree of versatility is provided to the designer interms of the patterns which can be extruded in accordance with thepresent invention. Multiple layers of the same color can be provided inone portion of the width of the sheet material while adjacent portionsinclude alternating colors. In addition to truly colored or pigmentedmaterials pearlescent and metallic components may be provided in astream of the same color as that employed in an adjacent layer toprovide unusual effects.

As shown in FIGS. 7-10, a band of color may be tapered in width throughthe depth of the sheet material to provide decreasing intensity of thatcolor through the tapering portion. This type of material simulates thegradient density sheet material described and claimed in the US. Pat.No. 2,985,556, granted May 23, 1961, to William P. Rowland.

It will also be appreciated that motion may be superimposed upon thelayered streams to further vary the disposition of the differentiallycolored portions and to upset or otherwise modify the positioning of thepearlescent and metallic flake materials within the body of the sheetmaterial.

The spacer and flow elements may be fabricated so as to be relativelyinterchangeable in the color distributing stack to make various types ofpatterns, particularly when the notched-out apertures in the flowelements are asymmetric with respect to the width thereof. For makingthicker layers, several flow elements having the same configuration ofapertures may be superimposed with relatively thin spacer elementstherebetween to minimize undue interference with the fiow of syntheticplastic material thereabove and therebelow. By varying the configurationof the notched-out apertures in the flow elements, the width anddisposition of the colored streams may be widely varied so long asprovision is made for adequate fiow of synthetic thermoplastic materialto fill the aperture at its widest portion and minimize trailing at theedges between two differentially colored materials.

Although various arrangements may be employed such as providing allconduits above or below the stack, one convenient arrangement locatesone conduit above and another conduit below the color distributing stackand both extend across the width thereof. The manifolds extend upwardlyfrom the lower conduit and downwardly from the upper conduit in spacedrelationship transversely of the color distributing stack, preferably inalignment to minimize variation in flow and pressure differentials. Suchan arrangement normally will utilize a cross-head extruder arrangementwherein the main extruder feeds to the rear of the extrusion die and theconduit from the extruder expands inwardly to the color distributingstack and extends across the width thereof to enable the severalmanifolds to be fed therefrom. The cross-head extruder directly feeds toa conduit extending across the width of the color distributing stack andenables the several cooperating manifolds to be fed therefrom.

Generally, a multiplicity of manifolds will extend through the colordistributing stack. Although as few as three manifolds may be employedwith limitations on versatility, generally at least seven and preferablytwelve or more are employed to obtain highly effective flow of thesynthetic plastic material. Depending upon the extruders, the thicknessof the flow elements, and the width and thickness of the sheet material,even more manifolds may be desirable for some installations. Generally,al-

though adjacent manifolds may carry the thermoplastic d material fromdifferent conduits, a series of adjacent manifolds may be fed by thesame conduit for a monocolored portion of the width of the sheetmaterial or for special effects where the distribution of the othercolor to that portion may be impeded for the desired pattern.

The flow elements and spacer elements are generally plate-like membersassembled in a stack so as to provide spacer elements between one ormore flow elements defining a layer. Although the spacer elements aregenerally unapertured, the flow elements are apertured as by notches orslots to provide paths therein from the manifolds to the edge adjacentthe extrusion die orifice. To provide for a substantially uniform layeror width of a color encompassing two manifolds of that color separatedby a manifold of another color, the slots or notches defining theapertures from the manifolds expand the width toward the edge adjacentthe extrusion die orifice and desirably converge with adjacent slots ornotches to minimize spacing therebetween.

It will be appreciated that more than two differentially coloredsynthetic plastic materials may be employed in accordance with thepresent invention by providing additional conduits and manifoldsconnected to the various conduits. In such a method and apparatus,various apertures in the flow elements communicate with the manifoldsfor the several colors and are so configured as to provide overlyingflow of streams of differentially colored thermoplastic material fromthe various conduits in any desired arrangement. In accordance with oneaspect of the invention, the flow from each of the conduits may beprovided to the depth of the combined stream at a portion of the widththereof or various combinations of the several colors may be so combinedto provide the full depth at any one point. In addition, layerscontaining more than one color may be formed by having the apertures inthe flow elements configured to provide side-by-side flow of streams ofmolten thermoplastic material from more than one conduit. In thismanner, various patterns of the differentially colored material throughthe depth and width of the sheet may be obtained.

It will be appreciated that the number of layers of differentiallycolored material may be varied widely. Although as few as three layerswill provide the differenti ally colored layered effect of the presentinvention, generally it is desirable to provide four to ten layers. Asmany as twenty, and even more, layers may be provided depending upon thethickness of the material being extruded but factors of fluid dynamicsin thin stream layers must be considered in determining the number oflayers that may be employed for a given thickness of material.

Because of the effect of fluid dynamics and static flow across thesurfaces of the spaces and flow elements, it is generally desirable tohave a minimum thickness of about 0.03 inch for the stream of colorbetween the spacer elements. However, as the thickness of the stream isincreased over the range of the next 0.10 inch, the flow increasesexceedingly rapidly so that it is often desirable to make a thick layerbetween thinner layers as a composite of several stream layers of thatcolor separated by spacer elements to avoid excessive fluid pressurewhich would distort the differentially colored layers thereabove andtherebelow. For example, a flow element of 0.047 inch thickness betweenspacer elements may produce a stream layer of 0.010 inch while a flowelement of 0.063 inch thickness between spacer elements produces astream of 0.038 inch. Thus, to produce a stream of 0.020 inch withgreater control, it is desirable to employ two of the smaller flowelements separated by a spacer element, desirably of about 0.015 inch.Similarly, even thicker streams of a single color may be compiled by useof small thickness flow elements to obtain greater control of the thickstreams.

The flow elements should have the flow apertures therein configured soas to supply sufficient molten material to avoid erratic edges betweenlayers or adjacent bands of color depending upon the color formationdesired. Where the sides of adjacent apertures in the flow elementsconverge toward the extrusion die orifice, the flow elements shouldprovide a flow path of sufficient length to permit flow of sufficientmaterial to such points of convergence for effecting uniformity of thethickness of the layer to such points and/or the flow elements shouldhave a sufficiently high number of manifolds extending therethrough fromthe conduits so that a greater number of flow apertures of smaller widthcan be employed to effect the desired sufficiency of flow.

Although the spacer elements desirably extend to the end of the stackadjacent the extrusion die orifice, it may be desirable to have thespacers, or portions thereof, of greater or lesser length than the flowelements so that they extend beyond or terminate short of the end of theflow elements in at least portions thereof. By using shorter spacerelements, disturbance in the regularity of the adjacent stream layersmay be effected by use of a stream of higher flow rate and various flowpatterns in the differentially colored material or special effects canbe superposed thereon. For example, by providing a pair of adjacent flowelements for a single color separated by a spacer element configured sothat its edge adjacent the extrusion die orifice is recessed inwardly ofthe color distributing stack at one point and tapers outwardly therefromover a portion of the width of the spacer element, it is possible toobtain sheet material having a layer of tapering thickness over aportion thereof. The stream of the color formed by the separated flowplates will be of greater width adjacent the deeply recessed portion ofthe recessed edge due to reduced resistance to flow along the surfacesof the spacer element and will taper to a reduced thickness as therecessed edge tapers outwardly. Similar effects can be obtained byrecessed edge spacers above and below a flow element of slightly greaterthickness than the fiow elements of the encapsulating streams due to thereduced static pressures of the encapsulated stream, with theencapsulating streams of another color disposed thereabove andtherebelow being of reduced dimension.

In another structure, the manifold-s supplying the colors may be widelyspaced across the width of the color distributing stack and the flowapertures thus caused to diverge considerably. When the thickness of theflow elements is sufficiently small in such a structure, the undulationsin the width of the layer-s of colors will be apparent due to the effectof fluid dynamics since the velocity and flow volume of thedifferentially colored materials will be varying across the width of thesheet material. By crimping or otherwise deforming the edge of thespacer elements adjacent the extrusion die orifice, undulations in thedifferentially colored materials may also be provided throughdisturbance of the flow thereof.

Thus, it can be seen that the present invention provides a novel andattractive synthetic plastic sheet material having generallylongitudinally extending layers of differentially colored material whichmay provide a wide variation in patterns. The present invention providesa relatively simple and highly efficacious method for producing suchsheet material having longitudinally extending layers of differentiallycolored material.

By use of relatively economically and simply fabricated components inthe method, the designer may create numerous pattern designs containingboth multicolored layers and multicolored bands across the width of thesheet material. Such sheet material has a wide variety of applicationsand is particularly adapted to the fabrication of eyeglass frameswherein beveling of the edge portions thereof will expose themulticolored layers.

Having thus described the invention, I claim:

1. In the method of making synthetic thermoplastic sheet material havingdifferentially colored layers in at least a portion thereof, the stepscomprising: providing a first stream of fluid synthetic thermoplasticmaterial; providing a second stream of differentially colored fluidsynthetic thermoplastic material; passing said first and second streamsthrough separate manifolds in a color distributing stack of amultiplicity of spacing and flow elements; causing material from one ofsaid streams to flow from one manifold through a flow element; causingmaterial from the other of said streams to flow from another manifoldthrough another flow element above said first-mentioned flow element andseparated therefrom by a spacing element with said material issuing fromsaid flow elements combining to provide a compo-site stream outwardly ofsaid stack having differentially colored layers in at least a portion ofthe width thereof; and extruding said composite stream to provide asynthetic thermoplastic sheet material having differentially coloredlayers in at least a portion of the width thereof.

2. The method of claim 1 wherein said material flowing from said one andanother manifold expands in width as it passes through the colordistributing stack.

3. The method of claim 1 wherein material is caused to flow in anadjacent path through one of said flow elements from manifoldscommunicating with both of said conduits so as to provide differentiallycolored bands within the same layer.

4. The method of claim 1 wherein the material flowing from one of saidstreams distorts the thickness of the material flowing from the other ofsaid streams in at least a portion of the width thereof to providedifferentially colored layers of varying thickness.

5. In the method of making synthetic thermoplastic sheet material havingdifferentially colored layers in at least a portion thereof, the stepscomprising: providing a first stream of fluid synthetic thermoplasticmaterial; providing a second stream of differentially colored fluidsynthetic thermoplastic material; providing a third stream ofdifferentially colored fluid synthetic material thermoplastic material;passing said first, second and third streams through separate manifoldsin a color distributing stack of a multiplicity of spacing and flowelements; causing material from one of said streams to flow from onemanifold through one flow element; causing material from said secondstream to flow from another manifold through another flow element abovesaid first-mentioned flow element and separated therefrom by a spacingelement; causing material from said third stream to flow from yetanother manifold in yet another flow element separated from adjacentflow elements by spacing elements, said material issuing from saidseveral flow elements combining to provide a composite stream outwardlyof said stack having three differentially colored layers in at least aportion of the width thereof; and extruding said composite stream toprovide synthetic thermoplastic sheet material having threedifferentially colored layers in at least a portion of the widththereof.

6. The method of claim 5 wherein material is caused to flow in adjacentpaths through one of said flow elements from manifolds from each of saidstreams to provide three differentially colored bands in the same layer.

References Cited UNITED STATES PATENTS 2,985,556 5/1961 Rowland l562443,370,999 2/1968 Schwarzrock l56244 X 3,443,278 5/1969 Nauta 18-13BENJAMIN R. PADGETT, Primary Examiner S. J. LECHERT, 111., AssistantExaminer US. Cl. X.R.

